Main menu

Post navigation

Battery Charger Circuit Boards: Care & Repair

Recently, we had a service call to repair a battery charger for a local business which was not operational. The charger has been stored outside for years with little to no protection from the elements. Below we discuss our findings below and the condition of the battery charger circuit boards within.

Initially, the customer had reported that the Powerwise battery charger would not turn on when plugged in. Their EZGO TXT was completely dead due to lack of charge. Since, this cart is used by a business for operations, we decided it was best to bring both the golf cart and the battery charger to our shop for inspection. An issue could be present in either the cart or charger which can produce such an issue.

Inside the Powerwise brand charger, there are several battery charger circuit boards, They are called the power input board, and control board, respectively. In later models, these boards were combined into a single board. In a nutshell, the battery charger circuit boards inside this unit are responsible for the charge process. When plugged into the cart, the battery charger circuit boards are responsible for “sensing” the state of charge within the battery bank. They are also responsible for applying sufficient power to raise that charge level, monitoring during the charge process, and then turning off the charger when the desired charge level is reached.

As you can see from the pictures , the battery charger circuit boards in this example did not stand a fighting chance. Like most electronic circuit boards, it is not water-proof, can be temperature sensitive and achieves its best performance in controlled environments. This charger was left outside for several years with no protection whatsoever from the elements. As you can see, not only were signs of water were present but also the battery charger circuit boards were so covered with debris that it could barely be seen.

There is not a great test for battery charger circuit boards in terms of voltage or resistance readings. Initially, the fuse and diodes tested good, which are common to fail, so we then focused our attention to the board in question. You can either substitute the possible bad board with a known good one and see if it works. If you don’t have another board laying around, you can bypass the relay for test purposes.

Before doing so, be sure the charger is unplugged from both the wall and vehicle. Also, be sure to remove all jewelry, rings, watches, etc. This is a good practice to observe any time you are working with electricity. Remove the two wires leading into the battery charger circuit board relay. The relay is the black cube on the board. The two wires will need to be connected to each other with a jumper wire, paper clip, etc. This effectively bypasses the relay. Plug into the wall first, then the cart. If it turns on and the ammeter moves, it should be fixed.

The battery charger circuit board should be replaced immediately. Do not use it to complete the charge process! By bypassing the board, you have effectively removed the safety cut-off feature it controls to shut the charger down when the proper charge level is achieved. See newly installed board below.

10 thoughts on “Battery Charger Circuit Boards: Care & Repair”

I am having a problem with my charger with overcharging. I have a 1996 EZGO TXT with a 36 volt system and a Powerwise Charger. The charger is putting out 66 volts.

I tested my batteries (brand new by the way) and they actually read 53 volts. I had the charger on them for a few hours. I plugged in the charger and the charger was putting out the 66 volts. The ammeter shot up to 20 amps when first plugged in but then dropped down to 11 and steadied there, still charging the batteries.

I obviously don’t want to wreck my new batteries, what would be the problem?

Would running my 36 volt golf cart at that high of voltage hurt it ? I would need a way to drain down the batteries otherwise.

Apologies for the lack of a reply on this one. Did you ever get this figured out? You definitely shouldn’t operate a 36V cart at such a high voltage, although I am unsure as to why the Powerwise charger would be putting out voltage of that magnitude.

Hi I am having QN issue with a 97 ezgo txt 36 volt power wise charger …the charger when plugged into the cart will come on and hum but stays stuck on 20 for hours and the charger gets a little hot …it doeasnt seem to be charging the cart the cart is now dead because the charger isn’t charging it been stuck on this for weeks now and can’t seem to figure this out don’t have the money for a shop so trying to fix myself just need help on what this could be ….any and all info is greatly appreciated…. this is a yard working sometimes yard toy cart

It could be a number of possibilities. But, more information would need to be known for further diagnosis. Does the ammeter on the front of the charger, jump up and show amperage? if so, what does it read? It should start out on the high side of the gauge and gradually drop the amperage down as the charge progresses. 20 hours is way to long and regardless if the charge is complete or not, I think the circuit board should shut it down by then for safety reasons. I would also be interested to know the age of the batteries. Typically, they don’t last more than 4-6 years even with impeccable maintenance. As they age, they may take a lot longer to charge than when new, but certainly not 20 hours. Not terribly concerned about the charger getting a little hot. Many ferro-resonant transformer charger do this even under normal circumstances.

You should also test the output. With a voltmeter, measure across your main positive and main negative of your battery bank. The two wires out of the back of the charger receptacle should lead you to the proper terminals. You should get approximately 36V at rest, unless they are discharged then likely less. if it’s way less, you could have a single or multiple bad batteries. Then, plug the charger into the cart and measure the voltage again. If the charger is working properly, the reading at the batteries should be around 40 volts of so. if that is the case, your charger would be working properly. If that checks out, but it’s still not cutting off, I’d say something is wrong with one of your circuit boards inside. Older models have two circuit boards, while new ones have a combo board. The combo board is the only one now available and could be retrofitted into an older model with two.

If the voltage at the batteries does not change with the charger plugged in, you have a bad diode inside. There are two inside. If both go bad, the charger won’t come on. if only one goes bad, the charger comes on, hums, and the ammeter goes up, but it doesn’t actually charge. To test the diodes, you unplug the charger form everything, cart and wall. Then disconnect the wires to the diodes. then, check from one end of the diode to the other with your ohmmeter, you should have continuity one way but not the other since a diode is a one way gate for electricity. If you have continuity both ways or neither way, it is bad and needs replacing.

I recently purchased a 2003 Western Electric Golf Car. I need to purchase a battery charger and the charging cable, but I don’t know what I should purchase or where to get it. Any help would be greatly appreciated.

I have an EZ-Go cart and a Pro Fit charger. 6, 6 amp Trojan Batteries. I forgot to plug the charger in this winter. Dead batteries. Thought it was the charger. Figured out I needed to charge the batteries enough to get the Pro-Fit to read that the batteries were there and turn itself on. Now the Pro-Fit keeps flashing the yellow light, the amp meter reads no more than 5 amps and it won’t charge the batteries. Batteries are new last year and the charger was bought 2 years ago. When I check the voltage of the batteries they each read 5.7 to 5.9. Not sure what to do or check next. Thank You.

A basic voltage check won’t do much to give you an idea of overall battery health. They need to be load tested with either a 50A load per battery or an overall load of about 300A across the bank. Bad batteries can often display reasonable voltage when sitting at rest without a load. While, when a load is applied, they may drop several volts which is not acceptable. Generally speaking, a load tested battery shouldn’t drop more than about a volt under load. You might want to either by a load tester to check those out or have them professionally tested. It can often shows signs of issues that cannot be found elsewhere.

The problem could also be with the charger. You could have a bad diode inside. Generally most chargers have at least diodes. If both diodes fail, the charger won’t work at all. but if one fails, it may come on and almost function normally. Check the voltage at the main battery bank positive and negative and it should be somewhere around 36V or so. Then, plug in the charger and measure the voltage again. If should jump up to around 40V or so. If it stays at the same voltage and doesn’t move, you definitely have a bad diode.